It was the morning after my first overnight call as an intern. I was nervous and reeked of sweat. Dr. Kia Afshar, youthful and rested, with buzzcut hair, leaned on a folding shelf outside a hospital room. Inside was the patient I had admitted for hypotension and decompensated heart failure. A ring of white coats—interns, residents, medical students—formed around Dr. Afshar. He took my H&P and turned it over to use as scratch paper. The white coats leaned in for a closer look.

Dr. Afshar drew four vertical lines. He hatched them with horizontal lines. He labeled the columns: Mechanism of Circulatory Shock, Right Atrial Pressure, Cardiac Output, and Systemic Vascular Resistance. He labeled the rows: Hypovolemic, Distributive, and Cardiogenic.